1. Field of the Invention
The present invention relates to a micromechanical component having a diaphragm structure which is implemented in a layered structure on a substrate. The diaphragm structure includes a diaphragm which is integrated via at least one spring element into the layered structure and spans a cavern, so that at least one section of the diaphragm edge extends up to and beyond the edge area of the cavern. At least one anchoring structure is formed in the overlap area between the diaphragm and the cavern edge area.
2. Description of the Related Art
The diaphragm structure of a micromechanical component may be devised for various applications, e.g., as a diaphragm for detecting pressure, as a microphone or a loudspeaker diaphragm, or also as a closing element of a micromechanical valve. Since the mechanical stress state of the diaphragm in most cases has an effect on the functionality of the component, the diaphragm should have a preferably precisely defined mechanical stress state in the case of applications of this type. Under certain circumstances, this requires compromises when it comes to the material selection and/or the actually implemented stress state. In any case, manufacture-related mechanical stress states already occur in the diaphragm layers which are often not optimally suitable for the particular component functions.
One important application for the micromechanical components having a diaphragm structure which are discussed here is the utilization as a microphone component. Microphone diaphragms should preferably be stress-free and, at the same time, be preferably closed off all around in an airtight manner, so that there is preferably little flow around the diaphragm edge.
In US Patent Application Publication No. 2006/0280319 A1, a microphone component of the type mentioned at the outset is described. The microphone structure of this micromechanical component is implemented in a layered structure on a semiconductor substrate and spans a cavern in the substrate back side. The microphone structure includes a diaphragm and a fixed, acoustically permeable counter element including through openings. In the present case, the counter element is located below the diaphragm, i.e., between the substrate and the diaphragm. It is used as a carrier of a fixed electrode which, together with an electrode on the deflectable diaphragm, forms a capacitor system for signal detection. The diaphragm is integrated into the layered structure merely via one or multiple cantilever beam(s), so that manufacture-related mechanical stresses may be well relieved within the diaphragm. The diaphragm extends up to and beyond the edge area of the cavern, where a circumferential groove is formed at the diaphragm edge in the layered structure. This groove is primarily used for acoustically sealing the diaphragm, but also functions as an anchoring structure and an overload protection.